Search PubMed⌕ Search

Biomedical subjects

R Tanaka

Publications and source records attributed to R Tanaka.

At least 847 records · Page 47Linked to original sources
PubMed1979

Glycoprotein galactosyltransferase activity in synaptic junctional complexes isolated from rat forebrain.

A synaptosomal plasma membrane fraction and its junctional and nonjunctional subfractions were isolated and analyzed for glycoprotein galactosyltransferase activity. The nonjunctional components fraction had the highest specific activity in the presence of exogenous acceptor, suggesting an enrichment of enzyme in this fraction. The synaptic junctional complex fraction had the highest specific activity in the absence of added acceptor, suggesting that there is a relative enrichment of endogenous acceptors for this galactosyltransferase within the synaptic junctional complex.

Animals↗
PubMed1979

Stimulation by subsynaptosomal fractions of transmitter efflux from plain synaptic vesicle fraction.

The effects were investigated of purified subsynaptic fractions on the efflux of radioactivity from a plain synaptic vesicle fraction which had incorporated [3H]dopamine. About 50% of the radioactivity incorporated into the plain vesicles (120 microgram protein) was liberated on exposure to purified synaptic membranes (30 microgram protein). The synaptic membrane-dependent efflux appeared to depend on both adenosine triphosphate and divalent cations, especially Ca2+. Of the sub-cellular fractions used, the heavy microsomal fraction showed the same effects as the synaptic membrane fraction. Purified synaptic junctions exhibited the strongest stimulating effects: the efflux was 2 times greater than that observed with synaptic membranes. The stimulating effects of myelin were less than one-seventh of those of synaptic junctional fraction. These observations may indicate that the transmitters are liberated by interaction of vesicle membrane with synaptic membrane in the presence of ATP and divalent cations.

Adenylyl Imidodiphosphate↗
PubMed1979

Anomeric specificity in the response of gut glucagon-like immunoreactive materials to glucose.

An anomeric specificity of the glucose sensors of A cells and B cells of the pancreas has been reported. In this context the present authors investigated, using the canine intestinal loop prepared from the terminal portion of the ileum, how glucagon-like immunoreactive materials (GLI) of the gut would respond to glucose anomers in an attempt to explore a possible anomeric specificity of glucose-stimulated gut GLI secretion. As a result GLI was found to be more readily released into the blood stream after an intestinal alpha-glucose load than following beta-gluocse during a 15-minute observation period. It is thus suggested that gut GLI-secreting cells have glucose sensors similar to those of pancreatic A or B cells which are specific for the alpha-glucose anomer.

Animals↗
PubMed1979

The presence of an adenosine-5'-triphosphatase dependent on 6S tubulin and calcium ions in rat brain microtubules.

An ATPase activity was found in rat brain microtubules prepared by successive cycles of polymerization and depolymerization. On phosphocellulose column chromatography, the ATPase activity was recovered in the fraction eluted with 0.6 M KCl and containing the microtubule associated proteins. The ATPase activity was markedly stimulated by the addition of purified brain 6S tubulin, and the stimulation was dependent on the presence of Ca2+ ions. Approximately 50 pmol of purified 6S tubulin was required for the maximal stimulation in the presence of 8 microgram of microtubule associated proteins. The specific activity was 8 to 13 nmol of ATP hydrolyzed per min per mg of protein at 37 degrees C, and the Km value for ATP was 3 X 10(-5) M in the presence of added tubulin.

Adenosine Triphosphatases↗
PubMed1979

Half life of gastrointestinal glucagon-like immunoreactive materials.

The composition, half life and hyperglycemic action of the porcine gastrointestinal glucagon-like immunoreactive materials were examined. Glucagon immunoreactivity (GI) measured using specific antiglucagon serum was more abundunt in the extract from the gastric fundus than in the one from the small intestine. When the extract from the gastric fundus was injected in dogs, the half life (T1/2) of total glucagon-like immunoreactivity (total GLI) measured using nonspecific antiglucagon serum was 9.5 +/- 1.1 min (mean +/- SEM), which was longer than that of crystalline pancreatic glucagon, 3.4 +/- 0.2 min, but shorter than that of the extract from the small intestine, 15.9 +/- 1.3 min. On the other hand, T1/2 for GI from the gastric fundus was 5.1 +/- 0.9 min, which was not significantly different from that of crystalline pancreatic glucagon. Blood sugar levels were significantly increased from the basal by 25 +/- 4 mg/100 ml at 10 min and 19 +/- 4 mg/100 ml at 15 min following an injection of the extract from the gastric fundus, but such a change in blood sugar levels was not demonstrated when the extract from the small intestine was injected. These results suggest that GI of the gastric fundus is close to pancreatic glucagon in respect of its metabolism and hyperglycemic activity.

Animals↗
PubMed1979

Computerized tomography of coagulation necrosis of the brain and brain tumors.

Diffuse contrast enhancement was observed on computerized tomography (CT) of coagulation necrosis of the brain and brain tumor. CT scans of delayed radiation necrosis of the brain seen in two patients showed a low absorption that was diffusely enhanced after an intravenous injection of contrast medium. Areas of central coagulation necrosis of anaplastic gliomas in two patients exhibited a marked contrast enhancement which was characterized by a prolonged increase in attenuation and a delayed elimination of the contrast medium.

Adult↗